In today’s world of special effects, one of the biggest challenges we all face stems from a single question: “How do we meet the high aesthetic expectations brands want, while addressing the concerns of regulatory pressures and rising cost?”
The good news is that these hurdles have been met head-on with innovations that take us to the next dimension of solutions for metallic ink printing. The diverse lineup of metallic inks today launches us to a new galaxy of packaging efficiency with some of the highest brilliance levels achieved.
Metallic effects on printed goods gain more and more importance as the trend continues to grow. The packaging and label industry strives to improve brand identification and brand recognition of products in the supermarket. The human eye is stimulated by shiny silver and bright golden effects, which is the reason these colors gain so much attention.
Today, there are a number of technologies on the market to obtain metallic effects on film-, paper- and carton-based packaging. All come with certain benefits and drawbacks. Metallic inks are hitting the mark by offering a high level of diversity and sophistication in packaging.
Match Any Application
Metallic effect pigmented inks are used in all market segments of the packaging and printing industry, using different binder chemistries and curing mechanisms for all printing applications. A challenge can be to find the best match between chemistry and market segment regulations (e.g., tobacco and food packaging), governmental regulations (e.g., VOC regulations, dangerous good regulations, low migration) and brand owner regulations (e.g., Nestlé), even though all solutions are available on the market. See Figure 1.
Metallic Pigments 101
In general, the appearance of a pigment with a lot of scattering area is different than a pigment with a lower scattering area. The area is defined by size and shape of the pigment that dictates the overall reflection of light back to the eye. The more surface area that is available with smoother edges, the higher the direct reflection of light, while the finer particles that reflect less light are responsible for providing the good hiding power.
To lower the area of pigment edges, some years ago thinner pigments were developed, resulting in very good mirror effects. The pigments technologies available today are known as Cornflake, Silverdollar, Platindollar and Metalure. These ultra-thin pigments show a very high distinctness in images, as can be seen in Figure 2.
The pictures in Figure 2 show the four different pigment types with each approximately 10-µm. in particle size. While using the same substrate and printing application, the applied inks contain metallic pigments of different particle size distribution, pigment shape and particle thickness. The pigment-to-binder ratio has been adjusted to meet the specific application requirements of each flake type. The difference in appearance (direct reflection rate/ gloss) on the reverse-printed film between these four grades is visually seen. The brilliance and mirror effect development can be rated as Metalure > Platindollar > Silverdollar > Cornflake.
In Figure 3, the increase of surface smoothness with different flake types can be observed and attributed to their lower particle thickness.
Pearl Pigment Effects
Whether they are used for automotive coatings, industrial paints, powder coatings, plastics or in the graphic industry, with pearlescent pigments available today, you can achieve outstanding effects. Their transparency and extremely pure color shades open up endless possibilities for creative applications.
Newer pigments are based on synthetically produced glass versus standard mica. Thin flakes of this raw material create unique pearlescent effects by means of high-end coatings and classifying technologies. The effect varies from silky gloss to glittering sparkle, depending on the particle size of the pigment. The new carrier of synthetic glass gives off brilliant optical characteristics when compared to conventional pearlescent pigments.
Figure 4: The sparkle of synthetic glass compared with natural mica and the high-resolution image of rough versus smooth surface.
Why use pearl? Because pearl pigments are beneficial in applications with special requirements with regard to weather and humidity resistance over metallic pigments. Synthetic glass flakes give an extraordinary three-dimensional look and a characteristic light reflection—similar to a polished diamond. Figure 4 shows the sparkle of synthetic glass compared with natural mica and the high-resolution image of rough versus smooth surface.
It’s “game on” in the search for innovative, robust metallic inks that raise the visual bar and meet strict regulatory requirements. Challenging trends have unleashed new approaches to the development of metallic inks, where already limited raw material choices became tighter. The good news is that the strong prevail and some interesting products have come out of development.
One example is the utilization of Metalure (PVD) pigment in newly created UV-LED formulation. A high sheen UV metallic has been around for years, but here the bar has been raised with a positive outcome. New approaches have launched a series of products that are excluding materials requested by Nestlé and meeting a greater number of governmental requirements.
Figure 5 and Figure 6: New brilliant silver inks, like Eckart’s ULTRASTAR UV, were born to meet the market’s regulatory trends. Results that reflect increased gloss and density make this an optimum ink choice for high-quality, foil-like silver.
These new brilliant silver inks, seen in Figure 5 and Figure 6, were born to meet the market’s regulatory trends. As an added bonus, the result of increased gloss and density make this an optimum ink choice for high-quality, foil-like silver at a reduced cost—win/win/win!
Another very exciting pigment-to-ink innovation is with the frequently requested “prismatic rainbow effect,” depicted in Figure 7. Prismatic ink has been around in solvent flexo for years; however, the demand for the same effect in UV flexo has not been met until now. Through the advancement of pigment stabilization and new UV-LED formulation materials, a new innovative solution for the printer was born.
In the coming months, there will be new offerings in the market for a Prismatic UV LED ink that will give narrow web printers an alternative to selectively print a holographic effect where needed (see Figure 8). This should give them more choices and opportunities to save cost while displaying a high-end, printed prismatic effect.
The packaging trends are clear and it is exciting to know that, regarding special effects, ink really does make it all possible!